From Longman Business Dictionary
conurbationcon·ur·ba·tion /ˌkɒnɜːˈbeɪʃənˌkɑːnɜːr-/ noun [countableC] British EnglishBrE a group of towns that have spread and joined together to form an area with a high population, often with a large city as its centrethe densely populated conurbations of Britain